Sclerostin Regulation, Microarchitecture, and Advanced Glycation End-Products in the Bone of Elderly Women With Type 2 Diabetes

Effects of diabetes on osteocytes

PURPOSE OF REVIEW

Better understanding of the mechanisms underlying skeletal dysfunction in the context of diabetes is needed to guide the development of therapeutic interventions to reduce the burden of diabetic fractures. Osteocytes, the 'master regulators' of bone remodeling, have emerged as key culprits in the pathogenesis of diabetes-related skeletal fragility.

RECENT FINDINGS

Both type 1 diabetes and type 2 diabetes cause chronic hyperglycemia that, over time, reduces bone quality and bone formation. In addition to acting as mechanosensors, osteocytes are important regulators of osteoblast and osteoclast activities; however, diabetes leads to osteocyte dysfunction. Indeed, diabetes causes the accumulation of advanced glycation end-products and senescent cells that can affect osteocyte viability and functions via increased receptor for advanced glycation endproducts (RAGE) signaling or the production of a pro-inflammatory senescence-associated secretory phenotype. These changes may increase osteocyte-derived sclerostin production and decrease the ability of osteocytes to sense mechanical stimuli thereby contributing to poor bone quality in humans with diabetes.

SUMMARY

Osteocyte dysfunction exists at the nexus of diabetic skeletal disease. Therefore, interventions targeting the RAGE signaling pathway, senescent cells, and those that inhibit sclerostin or mechanically stimulate osteocytes may alleviate the deleterious effects of diabetes on osteocytes and bone quality.

Techniques for advanced glycation end product measurements for diabetic bone disease: pitfalls and future directions

PURPOSE OF REVIEW

Multiple biochemical and biophysical approaches have been broadly used for detection and quantitation of posttranslational protein modifications associated with diabetic bone, yet these techniques present a variety of challenges. In this review, we discuss recent advancements and complementary roles of analytical (UPLC/UPLC-MS/MS and ELISA) and biophysical (Raman and FTIR) techniques used for characterization of glycation products, measured from bone matrix and serum, and provide recommendations regarding the selection of a technique for specific study of diabetic bone.

RECENT FINDINGS

Hyperglycemia and oxidative stress in diabetes contribute to the formation of a large subgroup of advanced glycation end products (AGEs) known as glycoxidation end products (AGOEs). AGEs/AGOEs have various adverse effects on bone health. Commonly, accumulation of AGEs/AGOEs leads to increased bone fragility. For example, recent studies show that carboxymethyllysine (CML) and pentosidine (PEN) are formed in bone at higher levels in certain diseases and metabolic conditions, in particular, in diabetes and aging. Detection and quantitation of AGEs/AGOEs in rare and/or precious samples is feasible because of a number of technological advancements of the past decade.

SUMMARY

Recent technological advancements have led to a significant improvement of several key analytical biochemistry and biophysics techniques used for detection and characterization of AGEs/AGOEs in bone and serum. Their principles and applications to skeletal tissue studies as well as limitations are discussed in this review.

Risk factors for lower bone mineral density in older adults with type 1 diabetes: a cross-sectional study

BACKGROUND

Type 1 diabetes is associated with lower bone mineral density (BMD) and increased fracture risk, but little is known regarding the effects of diabetes-related factors on BMD. We assessed whether these factors are associated with lower hip BMD among older adults with type 1 diabetes.

METHODS

This cross-sectional study was embedded in a long-term observational study, the Epidemiology of Diabetes Interventions and Complications study (EDIC), a cohort of participants with type 1 diabetes, who were originally enrolled in the Diabetes Control and Complications Trial (DCCT), and were followed-up for more than 30 years at 27 sites in the USA and Canada. All active EDIC participants were eligible except if they were pregnant, weighed above the dual-energy x-ray absorptiometry (DXA) scanner limit, had an implanted neurostimulator, or were not willing to participate. The primary study outcome was total hip BMD. Hip, spine, and radius BMD and trabecular bone score (TBS) were measured with DXA at an annual EDIC visit (2017-19). Time-weighted mean HbA_1c, kidney disease, and peripheral neuropathy were measured annually during EDIC, and retinopathy was measured every 4 years. Skin intrinsic fluorescence, a measure of advanced glycation end products (AGEs), and cardiac autonomic neuropathy were assessed once (2009-10) during EDIC.

FINDINGS

1147 of the 1441 participants who were enrolled in the DCCT trial remained active EDIC participants at the start of this cross-sectional study. Between Sept 20, 2017, and Sept 19, 2019, 1094 of 1147 participants were screened for the EDIC Skeletal Health study. 1058 participants completed at least one of a set of DXA scans and were included in the analysis. 47·8% were women and 52·2% were men, 96·6% were White and 3·4% were of other race or ethnicity. The mean age of participants was 59·2 years (SD 6·7). Higher mean HbA_1c, higher skin intrinsic fluorescence, and kidney disease (but not retinopathy or neuropathy) were independently associated with a lower total hip BMD. Total hip BMD differed by -10·7 mg/cm² (95% CI -19·6 to -1·7) for each 1% increase in mean HbA_1c, -20·5 mg/cm² (-29·9 to -11·0) for each 5 unit higher skin intrinsic fluorescence, and -51·7 mg/cm² (-80·6 to -22·7) in the presence of kidney disease. Similar associations were found for femoral neck and ultra-distal radius BMD, but not for lumbar spine BMD or TBS.

INTERPRETATION

Poorer glycaemic control, AGE accumulation, and kidney disease are independent risk factors for lower hip BMD in older adults with type 1 diabetes. Maintenance of glycaemic control and prevention of kidney disease might reduce bone loss and ultimately fractures in this population. Osteoporosis screening might be particularly important in people with these risk factors. Further research to identify AGE blockers could benefit skeletal health.

FUNDING

National Institute of Diabetes and Digestive and Kidney Disease.

Glycaemic Control in Patients Undergoing Percutaneous Coronary Intervention: What Is the Role for the Novel Antidiabetic Agents? A Comprehensive Review of Basic Science and Clinical Data

Coronary artery disease (CAD) remains one of the most important causes of morbidity and mortality worldwide, and revascularization through percutaneous coronary interventions (PCI) significantly improves survival. In this setting, poor glycaemic control, regardless of diabetes, has been associated with increased incidence of peri-procedural and long-term complications and worse prognosis. Novel antidiabetic agents have represented a paradigm shift in managing patients with diabetes and cardiovascular diseases. However, limited data are reported so far in patients undergoing coronary stenting. This review intends to provide an overview of the biological mechanisms underlying hyperglycaemia-induced vascular damage and the contrasting actions of new antidiabetic drugs. We summarize existing evidence on the effects of these drugs in the setting of PCI, addressing pre-clinical and clinical studies and drug-drug interactions with antiplatelet agents, thus highlighting new opportunities for optimal long-term management of these patients.

Biochemical Markers of Aging (Advanced Glycation End Products) and Degeneration Are Increased in Type 3 Rotator Cuff Tendon Stumps With Increased Signal Intensity Changes on MRI

BACKGROUND

Advanced glycation end products (AGEs) are end products of protein glycation that bind to the receptor for AGEs (RAGE) and activate nicotinamide adenine dinucleotide phosphate oxidase (NOX), resulting in increased oxidative stress and rotator cuff fragility. Stump classification using the signal intensity ratio of the tendon rupture site to the deltoid muscle in the coronal view of T2-weighted fat-suppressed magnetic resonance imaging (MRI) scans is an indicator of clinical outcomes after rotator cuff repair surgery. Comparing the signal intensities of the deltoid (D) and rotator cuff tears (C), Ishitani et al. classified C/D <0.8 as type 1, 0.8 to 1.3 as type 2, and >1.3 as type 3.

HYPOTHESIS/PURPOSE

It was hypothesized that the oxidative stress and collagen degeneration that occur in the rotator cuff due to accumulation of AGEs can be assessed on MRI scans (stump classification). Therefore, this study aimed to compare AGE-related factors in the rotator cuff tear site tissues based on stump classification.

STUDY DESIGN

Descriptive laboratory study.

METHODS

The authors included 30 patients (11 with type 1, 9 with type 2, and 10 with type 3; mean age, 62.3 years) who underwent surgery for complete rotator cuff tears at our hospital. Tendon tissue was harvested from the torn rotator cuff site during surgery for tissue and cell evaluation.

RESULTS

There was no significant difference in the mean age according to stump classification. The number of patients with diabetes was significantly larger in type 3 than in the other types (P < .05). Tissue evaluation showed significantly higher expression of AGE and RAGE staining in type 3 than in the other types (~6.7-fold; P < .01). Cell evaluation showed that the expression rates of reactive oxygen species and apoptosis were significantly higher in type 3 than in the other types (~4.3-fold; P < .01). Gene expression by real-time polymerase chain reaction showed significantly higher RAGE (~5.1-fold), NOX (~5.3-fold), and IL (~3.0-fold) in type 3 than in the other types (P < .05).

CONCLUSION

Stump classification type 3 exhibited the highest accumulation of AGEs and the highest oxidative stress and apoptosis, suggesting a high degree of degeneration and inflammation. Imaging based on stump classification reflects the degeneration and fragility of the torn rotator cuff site.

CLINICAL RELEVANCE

This study provides evidence of a relationship between stump classification, which reflects rotator cuff fragility on MRI, and pathologies related to advanced glycation end products.

A novel methodological approach to simultaneously extract high-quality total RNA and proteins from cortical and trabecular bone

Molecular differences between cortical and trabecular bone, of relevance to understanding the pathophysiological basis of bone diseases, can be determined only through effective isolation methods for RNA and proteins. Here we present a TRIzol-based method, which combines bone pulverization and homogenization to extract simultaneously total RNA and proteins from human cortical and trabecular bone from the same carrot. RNA integrity and purity were determined as the 260/280 nm and 260/230 nm absorbance ratios and the 28S/18S rRNA ratio. Protein integrity and quality were evaluated by Coomassie blue staining. Reverse transcription quantitative polymerase chain reaction and immunoblotting for bone-specific genes and proteins were performed to verify the suitability of the isolated material in downstream applications. The 260/280 nm and 260/230 nm absorbance ratios were, on average, less than or equal to 1.8. Bands on agarose gel were consistent with intact RNA, with mean 28S/18S ratios of 1.68 ± 0.35 and 1.88 ± 0.10 for cortical and trabecular bone, respectively. Band patterns after Coomassie blue staining confirmed protein integrity. Successful gene and protein expression analysis, with relevant differences between the two compartments, highlighted the suitability of the material in downstream applications. The method presented here is appropriate and effective for the study of human bone.

Vitamin D in Osteosarcopenic Obesity

Osteosarcopenic obesity is a unique clinical condition where low bone and muscle mass coexist in individuals with obesity. Alterations in adipose tissue, skeletal muscle and bone are strictly interconnected, and vitamin D plays key roles in several metabolic pathways that are involved in maintaining musculoskeletal health and glucose homeostasis. We reviewed the available literature on mechanisms underlying osteosarcopenic obesity, with a focus on the role of vitamin D in the pathogenesis and treatment of the condition. We found that, although evidence from large observational studies and pre-clinical experiments strongly supports a role of vitamin D deficiency in the pathogenesis of osteosarcopenic obesity, the common belief that vitamin D improves musculoskeletal health lacks solid clinical evidence, as trials specifically aimed at assessing the effects of vitamin D supplementation in patients with osteosarcopenic obesity are not available, and trials that investigated the role of vitamin D on muscle and bone health in other patient populations either showed no or even detrimental effects. We conclude that large observational and interventional studies including individuals with osteosarcopenic obesity representative of different sex, age and race are needed to better define the role of vitamin D in the pathogenesis and treatment of this condition.

Distributions of Microdamage Are Altered Between Trabecular Rods and Plates in Cancellous Bone From Men With Type 2 Diabetes Mellitus

Individuals with type 2 diabetes mellitus (T2DM) have an increased risk of fragility fracture despite exhibiting normal to high bone mineral density (BMD). Conditions arising from T2DM, such as reduced bone turnover and alterations in microarchitecture, may contribute to skeletal fragility by influencing bone morphology and microdamage accumulation. The objectives of this study were (i) to characterize the effect of T2DM on microdamage quantity and morphology in cancellous bone, and (ii) relate the accumulation of microdamage to the cancellous microarchitecture. Cancellous specimens from the femoral neck were collected during total hip arthroplasty (T2DM: n = 22, age = 65 ± 9 years, glycated hemoglobin [HbA1c] = 7.00% ± 0.98%; non-diabetic [non-DM]: n = 25, age = 61 ± 8 years, HbA1c = 5.50% ± 0.4%), compressed to 3% strain, stained with lead uranyl acetate to isolate microdamage, and scanned with micro-computed tomography (μCT). Individual trabeculae segmentation was used to isolate rod-like and plate-like trabeculae and their orientations with respect to the loading axis. The T2DM group trended toward a greater BV/TV (+27%, p = 0.07) and had a more plate-like trabecular architecture (+8% BV_plates , p = 0.046) versus non-DM specimens. Rods were more damaged relative to their volume compared to plates in the non-DM group (DV_rods /BV_rods versus DV_plates /BV_plates : +49%, p < 0.0001), but this difference was absent in T2DM specimens. Longitudinal rods were more damaged in the non-DM group (DV_{longitudinal rods} /BV_{longitudinal rods} : +73% non-DM versus T2DM, p = 0.027). Total damage accumulation (DV/BV) and morphology (DS/DV) did not differ in T2DM versus non-DM specimens. These results provide evidence that cancellous microarchitecture does not explain fracture risk in T2DM, pointing to alterations in material matrix properties. In particular, cancellous bone from men with T2DM may have an attenuated ability to mitigate microdamage accumulation through sacrificial rods. © 2022 American Society for Bone and Mineral Research (ASBMR).

Associations of variability in body weight and glucose levels with the risk of hip fracture in people with diabetes

BACKGROUND

Diabetes is associated with a high risk of fragility fracture. However, there are controversies regarding the effect of fluctuations in metabolic parameters on the risk of fracture. We aimed to investigate the associations of body weight or glucose variability or their combination with the risk of hip fracture in people with diabetes.

METHODS

A population-based cohort study with 480,539 subjects over 40 years who had undergone three or more health examinations was performed. The degree of variability was evaluated using variability independent of the mean (VIM, 100 × standard deviation / mean^beta), coefficient of variation (CV), and average real variability (ARV, average of the absolute differences between consecutive values). High variability was defined as having values in the highest quartile. Cox proportional hazards models were used to estimate the risk of hip fracture.

RESULTS

There were 2834 hip fracture events (0.59%) during the mean follow-up of 8.1 years. After multivariable adjustment for age, sex, alcohol consumption, smoking, regular exercise, income, glucose, body mass index, hemoglobin, estimated glomerular filtration rate, diabetes duration, diabetes treatment with multiple agents, and osteoporosis, the HRs (95% CI) of hip fracture were 1.36 (1.24-1.50) and 1.29 (1.16-1.43) for high body weight VIM and high glucose VIM, respectively. The HR (95% CI) of both high VIM group was 1.63 (1.44-1.83), suggesting an additive effect of variabilities in body weight and glucose. The results were consistent when using CV and ARV and in various sensitivity analyses.

CONCLUSIONS

High variability in body weight and glucose levels is associated with an increased incidence rate and risk of hip fracture in people with diabetes.

The relative contribution of bone microarchitecture and matrix composition to implant fixation strength in rats

Bone microarchitectural parameters significantly contribute to implant fixation strength but the role of bone matrix composition is not well understood. To determine the relative contribution of microarchitecture and bone matrix composition to implant fixation strength, we placed titanium implants in 12-week-old intact Sprague-Dawley rats, ovariectomized-Sprague-Dawley rats, and Zucker diabetic fatty rats. We assessed bone microarchitecture by microcomputed tomography, bone matrix composition by Raman spectroscopy, and implant fixation strength at 2, 6, and 10 weeks postimplantation. A stepwise linear regression model accounted for 83.3% of the variance in implant fixation strength with osteointegration volume/total volume (50.4%), peri-implant trabecular bone volume fraction (14.2%), cortical thickness (9.3%), peri-implant trabecular crystallinity (6.7%), and cortical area (2.8%) as the independent variables. Group comparisons indicated that osseointegration volume/total volume was significantly reduced in the ovariectomy group at Week 2 (~28%) and Week 10 (~21%) as well as in the diabetic group at Week 10 (~34%) as compared with the age matched Sprague-Dawley group. The crystallinity of the trabecular bone was significantly elevated in the ovariectomy group at Week 2 (~4%) but decreased in the diabetic group at Week 10 (~3%) with respect to the Sprague-Dawley group. Our study is the first to show that bone microarchitecture explains most of the variance in implant fixation strength, but that matrix composition is also a contributing factor. Therefore, treatment strategies aimed at improving bone-implant contact and peri-implant bone volume without compromising matrix quality should be prioritized.

Vitamin D Supplementation for 12 Months in Older Adults Alters Regulators of Bone Metabolism but Does Not Change Wnt Signaling Pathway Markers

Vitamin D status and supplementation regulates bone metabolism and may modulate Wnt signaling. We studied the response of hormonal regulators of bone metabolism, markers of Wnt signaling and bone turnover and bone mineral density (BMD) and bone mineral content (BMC) in a randomized vitamin D intervention trial (12,000 IU, 24,000 IU, 48,000 IU/mo for 1 year; men and women aged >70 years; n = 379; ISRCTN35648481). Associations with total and free 25(OH)D concentrations were analyzed by linear regression. Baseline vitamin D status was (mean ± SD) 25(OH)D: 40.0 ± 20.1 nmol/L. Supplementation dose-dependently increased total and free 25(OH)D concentrations and decreased plasma phosphate and parathyroid hormone (PTH) (all p < 0.05). The procollagen 1 intact N-terminal (PINP)/C-terminal telopeptide (CTX) ratio, C-terminal fibroblast growth factor-23 (cFGF23), and intact FGF23 (iFGF23) significantly increased with no between-group differences, whereas Klotho was unchanged. 1,25(OH)₂D and PINP significantly increased in the 24 IU and 48,000 IU groups. Sclerostin (SOST), osteoprotegerin (OPG), receptor activator of NF-κB ligand (RANKL), BMD, BMC, and CTX remained unchanged. Subgroup analyses with baseline 25(OH)D <25 nmol/L (n = 94) provided similar results. Baseline total and free 25(OH)D concentrations were positively associated with 1,25(OH)₂D, 24,25(OH)₂D (p < 0.001), vitamin D binding protein (DBP) (p < 0.05), BMD, and BMC (p < 0.05). Associations with PTH (p <0.001), cFGF23 (p < 0.01), and BAP (p < 0.05) were negative. After supplementation, total and free 25(OH)D concentrations remained positively associated only with 24,25(OH)₂D (p < 0.001) and DBP (p < 0.001) and negatively with estimated glomerular filtration rate (eGFR) (p < 0.01). PTH and SOST were significantly associated only with free 25(OH)D. There were no significant relationships with BMD and BMC after supplementation. The decrease in PTH and increase in PINP/CTX ratio suggest a protective effect of supplementation on bone metabolism, although no significant effect on BMD or pronounced changes in regulators of Wnt signaling were found. The increase in FGF23 warrants caution because of its negative association with skeletal and cardiovascular health. Associations of total and free 25(OH)D with biomarkers were similar and known positive associations between vitamin D status and BMD were confirmed. The change in associations after supplementation might suggest a threshold effect. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Crosstalk Between Senescent Bone Cells and the Bone Tissue Microenvironment Influences Bone Fragility During Chronological Age and in Diabetes

Bone is a complex organ serving roles in skeletal support and movement, and is a source of blood cells including adaptive and innate immune cells. Structural and functional integrity is maintained through a balance between bone synthesis and bone degradation, dependent in part on mechanical loading but also on signaling and influences of the tissue microenvironment. Bone structure and the extracellular bone milieu change with age, predisposing to osteoporosis and increased fracture risk, and this is exacerbated in patients with diabetes. Such changes can include loss of bone mineral density, deterioration in micro-architecture, as well as decreased bone flexibility, through alteration of proteinaceous bone support structures, and accumulation of senescent cells. Senescence is a state of proliferation arrest accompanied by marked morphological and metabolic changes. It is driven by cellular stress and serves an important acute tumor suppressive mechanism when followed by immune-mediated senescent cell clearance. However, aging and pathological conditions including diabetes are associated with accumulation of senescent cells that generate a pro-inflammatory and tissue-destructive secretome (the SASP). The SASP impinges on the tissue microenvironment with detrimental local and systemic consequences; senescent cells are thought to contribute to the multimorbidity associated with advanced chronological age. Here, we assess factors that promote bone fragility, in the context both of chronological aging and accelerated aging in progeroid syndromes and in diabetes, including senescence-dependent alterations in the bone tissue microenvironment, and glycation changes to the tissue microenvironment that stimulate RAGE signaling, a process that is accelerated in diabetic patients. Finally, we discuss therapeutic interventions targeting RAGE signaling and cell senescence that show promise in improving bone health in older people and those living with diabetes.

Bone fragility in diabetes: novel concepts and clinical implications

Increased fracture risk represents an emerging and severe complication of diabetes. The resulting prolonged immobility and hospitalisations can lead to substantial morbidity and mortality. In type 1 diabetes, bone mass and bone strength are reduced, resulting in up to a five-times greater risk of fractures throughout life. In type 2 diabetes, fracture risk is increased despite a normal bone mass. Conventional dual-energy x-ray absorptiometry might underestimate fracture risk, but can be improved by applying specific adjustments. Bone fragility in diabetes can result from cellular abnormalities, matrix interactions, immune and vascular changes, and musculoskeletal maladaptation to chronic hyperglycaemia. This Review summarises how the bone microenvironment responds to type 1 and type 2 diabetes, and the mechanisms underlying fragility fractures. We describe the value of novel imaging technologies and the clinical utility of biomarkers, and discuss current and future therapeutic approaches that protect bone health in people with diabetes.

Circulating SIRT1 and Sclerostin Correlates with Bone Status in Young Women with Different Degrees of Adiposity

Sirtuin1 (SIRT1) and sclerostin play important roles in adipose tissue and bone metabolism. We evaluated the circulating SIRT1 and sclerostin relationship with mass and quality of bone while considering the degree of adiposity. Sixty-six premenopausal women (16 underweight, 25 normal weight and 25 with obesity), aged <50 years, were enrolled. Plasma SIRT1, sclerostin and DXA body composition (total fat mass (FM), abdominal visceral adipose tissue, lean mass, trabecular bone score (TBS) and lumbar spine and femoral neck (FN) bone mineral density (BMD)) were assessed. The patients with obesity showed the lowest SIRT1 and TBS values and the highest sclerostin concentrations; BMD increased with FM and BMI and had an inverse association with SIRT1. Sclerostin was negatively correlated with SIRT1 (ρ = −0.37, p = 0.002). When spine BMD, FN BMD and TBS were standardized for BMI, a positive correlation with SIRT1 and a negative correlation with sclerostin were seen (p < 0.005). In the regression analysis, sclerostin was the best independent, negative predictor for BMD and TBS, while SIRT1 directly predicted TBS (p < 0.05). In conclusion, blood measurement of SIRT1 and sclerostin could represent a snapshot of the bone status that, taking into account the degree of adiposity, may reduce the interference of confounding factors in the interpretation of bone health parameters.

The Impact of Diet on Bone and Fracture Risk in Diabetes

PURPOSE OF REVIEW

The purpose of this review is to summarize the recently published scientific evidence on the effects of diet on diabetes and skeletal health.

RECENT FINDINGS

The impact of diet on overall health has been a growing topic of interest among researchers. An inappropriate eating habit is a relatively modified risk factor for diabetes in adults. Parallel with the significant increase in the incidence of diabetes mellitus worldwide, many studies have shown the benefits of lifestyle modifications, including diet and exercise for people with, or at risk of developing, diabetes. In the last years, accumulating evidence suggests that diabetes is a risk factor for bone fragility. As lifestyle intervention represents an effective option for diabetes management and treatment, there is potential for an effect on bone health. Healthy lifestyle is critical to prevent bone fragility. However, more studies are needed to fully understand the impact of diet and weight loss on fracture risk in diabetics.

Greater Carboxy-Methyl-Lysine Is Associated With Increased Fracture Risk in Type 2 Diabetes

Accumulation of advanced glycation end-products (AGE) in bone alters collagen structure and function. Fluorescent AGEs are associated with fractures but less is known regarding non-fluorescent AGEs. We examined associations of carboxy-methyl-lysine (CML), with incident clinical and prevalent vertebral fractures by type 2 diabetes (T2D) status, in the Health, Aging, and Body Composition cohort of older adults. Incident clinical fractures and baseline vertebral fractures were assessed. Cox regression was used to analyze the associations between serum CML and clinical fracture incidence, and logistic regression for vertebral fracture prevalence. At baseline, mean ± standard deviation (SD) age was 73.7 ± 2.8 and 73.6 ± 2.9 years in T2D (n = 712) and non-diabetes (n = 2332), respectively. Baseline CML levels were higher in T2D than non-diabetes (893 ± 332 versus 771 ± 270 ng/mL, p < 0.0001). In multivariate models, greater CML was associated with higher risk of incident clinical fracture in T2D (hazard ratio [HR] 1.49; 95% confidence interval [CI], 1.24-1.79 per 1-SD increase in log CML) but not in non-diabetes (HR 1.03; 95% CI, 0.94-1.13; p for interaction = 0.001). This association was independent of bone mineral density (BMD), glycated hemoglobin (hemoglobin A1c), weight, weight loss, smoking, cystatin-C, and medication use. CML was not significantly associated with the odds of prevalent vertebral fractures in either group. In conclusion, higher CML levels are associated with increased risk of incident clinical fractures in T2D, independent of BMD. These results implicate CML in the pathogenesis of bone fragility in diabetes. © 2021 American Society for Bone and Mineral Research (ASBMR).

Circulating Sclerostin Levels Are Positively Related to Coronary Artery Disease Severity and Related Risk Factors

Romosozumab is a newly available treatment for osteoporosis acting by sclerostin inhibition. Its cardiovascular safety has been questioned after finding excess cardiovascular disease (CVD)-related events in a pivotal phase 3 trial. Previous studies of relationships between circulating sclerostin levels and CVD and associated risk factors have yielded conflicting findings, likely reflecting small numbers and selected patient groups. We aimed to characterize relationships between sclerostin and CVD and related risk factors in more detail by examining these in two large cohorts, Ludwigshafen Risk and Cardiovascular Health study (LURIC; 34% female, mean age 63.0 years) and Avon Longitudinal Study of Parents and Children study (ALSPAC) mothers (mean age 48.1 years). Together these provided 5069 participants with complete data. Relationships between sclerostin and CVD risk factors were meta-analyzed, adjusted for age, sex (LURIC), body mass index, smoking, social deprivation, and ethnicity (ALSPAC). Higher sclerostin levels were associated with higher risk of diabetes mellitus (DM) (odds ratio [OR] = 1.25; 95% confidence interval [CI] 1.12, 1.37), risk of elevated fasting glucose (OR 1.15; CI 1.04, 1.26), and triglyceride levels (β 0.03; CI 0.00, 0.06). Conversely, higher sclerostin was associated with lower estimated glomerular filtration rate (eGFR) (β -0.20; CI -0.38, -0.02), HDL cholesterol (β -0.05; CI -0.10, -0.01), and apolipoprotein A-I (β -0.05; CI -0.08, -0.02) (difference in mean SD per SD increase in sclerostin, with 95% CI). In LURIC, higher sclerostin was associated with an increased risk of death from cardiac disease during follow-up (hazard ratio [HR] = 1.13; 1.03, 1.23) and with severity of coronary artery disease on angiogram as reflected by Friesinger score (0.05; 0.01, 0.09). Associations with cardiac mortality and coronary artery severity were partially attenuated after adjustment for risk factors potentially related to sclerostin, namely LDL and HDL cholesterol, log triglycerides, DM, hypertension, eGFR, and apolipoprotein A-I. Contrary to trial evidence suggesting sclerostin inhibition leads to an increased risk of CVD, sclerostin levels appear to be positively associated with coronary artery disease severity and mortality, partly explained by a relationship between higher sclerostin levels and major CVD risk factors. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

No evidence of mineralization abnormalities in iliac bone of premenopausal women with type 2 diabetes mellitus

OBJECTIVES

Patients with type-2 diabetes mellitus (T2DM) have increased risk for bone fractures which points towards impaired bone quality.

METHODS

We measured bone mineralization density distribution (BMDD) and osteocyte lacunae section (OLS) characteristics based on quantitative backscattered electron images of transiliac biopsy samples from n=26 premenopausal women with T2DM. Outcomes were compared to those from reference cohorts as well as between T2DM subgroups defined by clinical characteristics.

RESULTS

Comparison to references did not reveal any differences in BMDD (all p>0.05) but a lowered OLS-density in cancellous bone in T2DM (-14.9%, p<0.001). Neither BMDD nor OLS-characteristics differed in T2DM subgroups defined by HbA1c (<7% versus >7%). The average degree of bone mineralization (CaMean) was higher (0.44 wt%Ca in T2DM, 0.30 wt%Ca in reference) and consistently the calcium concentration between the tetracycline double labels (CaYoung) was higher (0.76 wt%Ca, all p<0.001) in cancellous versus cortical bone.

CONCLUSIONS

Our findings suggest that bone matrix mineralization was neither affected by the presence nor by the glycemic control of T2DM in our study cohort. The intra-individual differences between cancellous and cortical bone mineralization gave evidence for differences in the time course of the early mineralization process in these compartments in general.

The role of advanced glycation end products in fracture risk assessment in postmenopausal type 2 diabetic patients

OBJECTIVE

The objective of this study was to analyze the quantitative association between advanced glycation end products (AGEs) and adjusted FRAX by rheumatoid arthritis (FRAX-RA) in postmenopausal type 2 diabetic (T2D) patients. The optimal cutoff value of AGEs was also explored, which was aimed at demonstrating the potential value of AGEs on evaluating osteoporotic fracture risk in postmenopausal T2D patients.

METHODS

We conducted a cross-sectional study including 366 postmenopausal participants (180 T2D patients [DM group] and 186 non-T2D individuals [NDM group]). All the subjects in each group were divided into three subgroups according to BMD. Physical examination, dual-energy x-ray absorptiometry (DXA), and serum indicators (including serum AGEs, glycemic parameters, bone turnover markers and inflammation factors) were examined. The relationship between FRAX-RA, serum laboratory variables, and AGEs were explored. The optimal cutoff value of AGEs to predict the risk of osteoporotic fracture was also investigated.

RESULTS

Adjusting the FRAX values with rheumatoid arthritis (RA) of T2D patients reached a significantly increased MOF-RA and an increasing trend of HF-RA. AGEs level was higher in the DM group compared to the NDMs, and was positively correlated with MOF-RA (r=0.682, P<0.001) and HF-RA (r=0.677, P<0.001). The receiver operating characteristic curve analysis revealed that the area under the curve was 0.804 (P<0.001), and the optimal AGEs cut-off value was 4.156mmol/L. Subgroup analysis for T2D patients revealed an increase in TGF-β, IL-6 and SCTX in the osteoporosis group, while a decreased PINP in the osteoporosis group compared to the other two subgroups. AGEs were positively associated with FBG, HbA1c, HOMA-IR, S-CTX, IL-6 and TGF-β in T2D patients, and negatively associated with PINP.

CONCLUSIONS

RA-adjusted FRAX is a relevant clinical tool in evaluating fracture risk of postmenopausal T2D patients. Our study analyzed the relationship between AGEs and FRAX-RA, and explored the threshold value of AGEs for predicting fracture risk in postmenopausal T2D patients. AGEs were also associated with serum bone turnover markers and inflammation factors, indicating that the increasing level of AGEs in postmenopausal T2D patients accelerated the expression of inflammatory factors, which led to bone metabolism disorders and a higher risk of osteoporotic fractures.

The Emerging Role of Bone-Derived Hormones in Diabetes Mellitus and Diabetic Kidney Disease

Diabetic kidney disease (DKD) causes the greatest proportion of end-stage renal disease (ESRD)-related mortality and has become a high concern in patients with diabetes mellitus (DM). Bone is considered an endocrine organ, playing an emerging role in regulating glucose and energy metabolism. Accumulating research has proven that bone-derived hormones are involved in glucose metabolism and the pathogenesis of DM complications, especially DKD. Furthermore, these hormones are considered to be promising predictors and prospective treatment targets for DM and DKD. In this review, we focused on bone-derived hormones, including fibroblast growth factor 23, osteocalcin, sclerostin, and lipocalin 2, and summarized their role in regulating glucose metabolism and DKD.

Update on the pathogenesis and treatment of skeletal fragility in type 2 diabetes mellitus

Fracture risk is increased in patients with type 2 diabetes mellitus (T2DM). In addition, these patients sustain fractures despite having higher levels of areal bone mineral density, as measured by dual-energy X-ray absorptiometry, than individuals without T2DM. Thus, additional factors such as alterations in bone quality could have important roles in mediating skeletal fragility in patients with T2DM. Although the pathogenesis of increased fracture risk in T2DM is multifactorial, impairments in bone material properties and increases in cortical porosity have emerged as two key skeletal abnormalities that contribute to skeletal fragility in patients with T2DM. In addition, indices of bone formation are uniformly reduced in patients with T2DM, with evidence from mouse studies published over the past few years linking this abnormality to accelerated skeletal ageing, specifically cellular senescence. In this Review, we highlight the latest advances in our understanding of the mechanisms of skeletal fragility in patients with T2DM and suggest potential novel therapeutic approaches to address this problem.

DXA parameters, Trabecular Bone Score (TBS) and Bone Mineral Density (BMD), in fracture risk prediction in endocrine-mediated secondary osteoporosis

Osteoporosis, a disease characterized by low bone mass and alterations of bone microarchitecture, leading to an increased risk for fragility fractures and, eventually, to fracture; is associated with an excess of mortality, a decrease in quality of life, and co-morbidities. Bone mineral density (BMD), measured by dual X-ray absorptiometry (DXA), has been the gold standard for the diagnosis of osteoporosis. Trabecular bone score (TBS), a textural analysis of the lumbar spine DXA images, is an index of bone microarchitecture. TBS has been robustly shown to predict fractures independently of BMD. In this review, while reporting also results on BMD, we mainly focus on the TBS role in the assessment of bone health in endocrine disorders known to be reflected in bone.

Can fingernail quality predict bone damage in Type 2 diabetes mellitus? a pilot study

Type 2 diabetes mellitus (T2DM) adversely affects the normal functioning, intrinsic material properties, and structural integrity of many tissues, including bone. It is well known that the clinical utility of areal bone mineral density (aBMD) is limited to assess bone strength in individuals with T2DM. Therefore, there is a need to explore new diagnostic techniques that can better assist and improve the accuracy of assessment of bone tissue quality. The present study investigated the link between bone and fingernail material/compositional properties in type 2 diabetes mellitus (T2DM). For that, femoral head and fingernail samples were obtained from twenty-five adult female patients (with/without T2DM) with fragility femoral neck fractures undergoing hemi/total hip arthroplasty. Cylindrical cores of trabecular bone were subjected to micro-CT, and lower bone volume fraction was observed in the diabetic group than the non-diabetic group due to fewer and thinner trabeculae in individuals with T2DM. The material and compositional properties of bone/fingernail were estimated using nanoindentation and Fourier Transform Infrared Spectroscopy, respectively. Both bone/fingernails in T2DM had lower reduced modulus (E_r), hardness (H), lower Amide I and Amide II area ratio (protein content), higher sugar-to-matrix ratio, and relatively high carboxymethyl-lysine (CML) content compared with non-diabetic patients. Sugar-to-matrix ratio and relative CML content were strongly and positively correlated with HbA_1c for both bone/fingernail. There was a positive correlation between bone and fingernail glycation content. Our findings provide evidence that the degradation pattern of bone and fingernail properties go hand-in-hand in individuals with T2DM. Hence, the fingernail compositional/material properties might serve as a non-invasive surrogate marker of bone quality in T2DM; however, further large-scale studies need to be undertaken.

Aging, obesity, sarcopenia and the effect of diet and exercise intervention

The number of adults 65 years and older is increasing worldwide and will represent the 20% of the population by 2030. Half of them will suffer from obesity. The decline in muscle mass and strength, known as sarcopenia, is very common among older adults with obesity (sarcopenic obesity). Sarcopenic obesity is strongly associated with frailty, cardiometabolic dysfunction, physical disability, and mortality. Increasing efforts have been hence made to identify effective strategies able to promote healthy aging and curb the obesity pandemic. Among these, lifestyle interventions consisting of diet and exercise protocols have been extensively explored. Importantly, diet-induced weight loss is associated with fat, muscle, and bone mass losses, and may further exacerbate age-related sarcopenia and frailty outcomes in older adults. Successful approaches to induce fat mass loss while preserving lean and bone mass are critical to reduce the aging- and obesity-related physical and metabolic complications and at the same time ameliorate frailty. In this review article, we discuss the most recent evidence on the age-related alterations in adipose tissue and muscle health and on the effect of calorie restriction and exercise approaches for older adults with obesity and sarcopenia, emphasizing the existing gaps in the literature that need further investigation.

Bone Marrow Adiposity in Premenopausal Women With Type 2 Diabetes With Observations on Peri-Trabecular Adipocytes

CONTEXT

No study has yet evaluated the relationships among bone marrow adiposity (BMA), bone histomorphometry (BH), and glycemic control in premenopausal women with type 2 diabetes (T2DM).

OBJECTIVE

We aimed to assess the effect of glycemic control on BMA, correlate the parameters of BH with BMA, and correlate BMA with the use of hypoglycemic agents and with bone mineral density (BMD).

METHODS

This was a cross-sectional study that evaluated 26 premenopausal women with T2DM who were divided into groups with HbA1c < 7% (good control [GC], n = 10) and HbA1c > 7% (poor control [PC], n = 16). BMA parameters (adipocyte number [Ad.N], total adipocyte perimeter [Ad.Pm], total adipocyte area [Ad.Ar], percentage adipocyte volume per marrow volume [Ad.V/Ma.V]) and peri-trabecular adipocyte number divided by bone surface (Ad.N/BS) were evaluated. BH static (bone volume fraction [BV/TV], osteoid thickness [O.Th], osteoid surface/bone surface [OS/BS]) and dynamic parameters and serum insulin-like growth factor-1 were measured. BMA data were compared between the GC and PC groups. Correlations were performed.

RESULTS

Ad.N, Ad.Pm, and Ad.Ar were higher in PC (all, P = 0.04). HbA1c correlated positively with Ad.N/BS (P < 0.01) and Ad.N/BS correlated negatively with O.Th (P < 0.01) and OS/BS (P = 0.02). Positive and negative correlations were observed between insulin and metformin use, respectively, with all adipocyte parameters except Ad.N/BS (P < 0.05). Structural parameters were negatively correlated with the BMA. BMD of the femoral neck (r = -549, P < 0.01) and total femur (r = -0.502, P < 0.01) were negatively correlated with Ad.V/Ma.V.

CONCLUSION

Poor glycemic control is associated with hyperplasia and hypertrophy of BMAs and with lower BV/TV. Ad.N/BS, a new BMA parameter, is correlated with HbA1c and negatively with O.Th. The use of insulin seems to stimulate the expansion of BMA while that of metformin has the opposite effect. These findings suggest that the increase in BMA may play a role in the T2DM bone disease; on the other hand, good glycemic control might help prevent it.

Association Between Visit-to-Visit Fasting Plasma Glucose Variability and Osteoporotic Fractures in Nondiabetic Subjects

CONTEXT

Although long-term glucose variability has been reported to be a risk factor associated with osteoporosis, there have been no previous studies between the relationship of glucose variability and fractures in people without diabetes.

OBJECTIVE

We assessed visit-to-visit variations in fasting plasma glucose (FPG) as a prognostic factor in predicting osteoporotic fractures in individuals without diabetes.

METHODS

Using a nationwide cohort database, we examined the impact of FPG on the development of osteoporotic fractures in men and women (aged ≥50 years). The primary outcomes were the number of total fractures and vertebral fractures. FPG variability was measured using standard deviation (FPG-SD), coefficient of variation (FPG-CV), and variability independent of the mean (FPG-VIM).

RESULTS

Of the 92 929 participants, 5262 (5.7%) developed osteoporotic fractures during the mean follow-up of 8.4 years. Individuals in the highest quartile of FPG-SD showed an 11% and 16% increase in risk of total and vertebral fractures, respectively, compared with those in the lowest quartile after adjustment for mean FPG and other risk factors. Analyses using FPG-CV and FPG-VIM demonstrated similar results. Subgroup analyses and sensitivity analyses to explore potential heterogeneity showed consistent results.

CONCLUSION

FPG variability may be a novel risk factor for osteoporotic fractures independent of risk factors in the general population without diabetes.

Association of bone biomarkers with advanced atherosclerotic disease in people with overweight/obesity

BACKGROUND

A growing body of evidence suggests a potential link between bone metabolism and cardiovascular disease. Aim of this study was to investigate the relationship between levels of circulating bone turnover biomarkers and advanced atherosclerosis.

METHODS

Klotho (KL), sclerostin (SOST), osteopontin (OPN) and osteoprotegerin (OPG) were measured in patients undergoing elective coronary angiography and carotid Doppler ultrasound. The primary outcome was the difference in bone biomarkers levels between participants with and without advanced atherosclerosis, defined as the presence of a critical coronary (≥70%) and/or carotid (≥50%) stenosis.

RESULTS

A total of 80 subjects (32.5% females) with a mean age of 68 ± 10 years were included. Advanced atherosclerosis was detected in 55 (68.8%) patients. Subjects with advanced atherosclerosis showed higher serum levels of OPG (p = 0.0015) and SOST (p = 0.017) and similar levels of KL (p = 0.62) and OPN (p = 0.06) compared to patients without. After adjustment for age and sex, only elevated levels of OPG remained significantly associated with advanced atherosclerosis (p = 0.011).

CONCLUSIONS

Higher serum levels of OPG are independently associated with advanced atherosclerosis confirming a common bond between bone metabolism and vascular disease. Further investigations on the role of selected bone biomarkers in the pathogenesis of cardiovascular disease are needed.

Advanced glycation endproducts and bone quality: practical implications for people with type 2 diabetes

PURPOSE OF REVIEW

Individuals with type 2 diabetes (T2D) are at increased risk of fracture, often despite normal bone density. This observation suggests deficits in bone quality in the setting of abnormal glucose homeostasis. The goal of this article is to review recent developments in our understanding of how advanced glycation end products (AGEs) are incorporated into the skeleton with resultant deleterious effects on bone health and structural integrity in patients with T2D.

RECENT FINDINGS

The adverse effects of skeletal AGE accumulation on bone remodeling and the ability of the bone to deform and absorb energy prior to fracture have been demonstrated both at the bench as well as in small human studies; however, questions remain as to how these findings might be better explored in large, population-based investigations.

SUMMARY

Hyperglycemia drives systemic, circulating AGE formation with subsequent accumulation in the bone tissue. In those with T2D, studies suggest that AGEs diminish fracture resistance, though larger clinical studies are needed to better define the direct role of longstanding AGE accumulation on bone strength in humans as well as to motivate potential interventions to reverse or disrupt skeletal AGE deposition with the goal of fracture prevention.

Testosterone Therapy Effects on Bone Mass and Turnover in Hypogonadal Men with Type 2 Diabetes

CONTEXT

Male hypogonadism is associated with low bone mineral density (BMD) and increased fragility fracture risk. Patients with type 2 diabetes (T2D) have relatively higher BMD, but greater fracture risk.

OBJECTIVE

Evaluate the skeletal response to testosterone therapy in hypogonadal men with T2D compared with hypogonadal men without T2D.

METHODS

Single arm, open-label clinical trial (NCT01378299) involving 105 men (40-74 years old), with average morning testosterone <300 ng/dL. Subjects were injected intramuscularly with testosterone cypionate (200 mg) every 2 weeks for 18 months. Testosterone and estradiol were assessed by liquid chromatography/mass spectrometry; serum C-terminal telopeptide of type I collagen (CTX), osteocalcin and sclerostin by enzyme-linked immunosorbent assay; glycated hemoglobin (HbA1c) by high-performance liquid chromatography, areal BMD (aBMD) and body composition by dual-energy x-ray absorptiometry; tibial volumetric BMD (vBMD) and bone geometry by peripheral quantitative computed tomography.

RESULTS

Among our population of hypogonadal men, 49 had T2D and 56 were non-T2D. After 18 months of testosterone therapy, there were no differences in circulating testosterone and estradiol between the groups. Hypogonadal men with T2D had increased osteocalcin, reflecting increased osteoblast activity, compared with non-T2D men (P < .01). T2D men increased lumbar spine aBMD (P < .05), total area at 38% tibia (P < .01) and periosteal and endosteal circumferences at the same site (P < .01 for both). T2D men had reduced tibial vBMD (P < .01), but preserved bone mineral content (P = .01). Changes in HbA1c or body composition were similar between the 2 groups.

CONCLUSION

Testosterone therapy results in greater improvements in the skeletal health of hypogonadal men with T2D than their nondiabetic counterparts.

The Cellular Choreography of Osteoblast Angiotropism in Bone Development and Homeostasis

Interaction between endothelial cells and osteoblasts is essential for bone development and homeostasis. This process is mediated in large part by osteoblast angiotropism, the migration of osteoblasts alongside blood vessels, which is crucial for the homing of osteoblasts to sites of bone formation during embryogenesis and in mature bones during remodeling and repair. Specialized bone endothelial cells that form "type H" capillaries have emerged as key interaction partners of osteoblasts, regulating osteoblast differentiation and maturation and ensuring their migration towards newly forming trabecular bone areas. Recent revolutions in high-resolution imaging methodologies for bone as well as single cell and RNA sequencing technologies have enabled the identification of some of the signaling pathways and molecular interactions that underpin this regulatory relationship. Similarly, the intercellular cross talk between endothelial cells and entombed osteocytes that is essential for bone formation, repair, and maintenance are beginning to be uncovered. This is a relatively new area of research that has, until recently, been hampered by a lack of appropriate analysis tools. Now that these tools are available, greater understanding of the molecular relationships between these key cell types is expected to facilitate identification of new drug targets for diseases of bone formation and remodeling.

Gain-of-Function Lrp5 Mutation Improves Bone Mass and Strength and Delays Hyperglycemia in a Mouse Model of Insulin-Deficient Diabetes

High fracture rate and high circulating levels of the Wnt inhibitor, sclerostin, have been reported in diabetic patients. We studied the effects of Wnt signaling activation on bone health in a mouse model of insulin-deficient diabetes. We introduced the sclerostin-resistant Lrp5^A214V mutation, associated with high bone mass, in mice carrying the Ins2^Akita mutation (Akita), which results in loss of beta cells, insulin deficiency, and diabetes in males. Akita mice accrue less trabecular bone mass with age relative to wild type (WT). Double heterozygous Lrp5^A214V /Akita mutants have high trabecular bone mass and cortical thickness relative to WT animals, as do Lrp5^A214V single mutants. Likewise, the Lrp5^A214V mutation prevents deterioration of biomechanical properties occurring in Akita mice. Notably, Lrp5^A214V /Akita mice develop fasting hyperglycemia and glucose intolerance with a delay relative to Akita mice (7 to 8 vs. 5 to 6 weeks, respectively), despite lack of insulin production in both groups by 6 weeks of age. Although insulin sensitivity is partially preserved in double heterozygous Lrp5^A214V /Akita relative to Akita mutants up to 30 weeks of age, insulin-dependent phosphorylated protein kinase B (pAKT) activation in vitro is not altered by the Lrp5^A214V mutation. Although white adipose tissue depots are equally reduced in both compound and Akita mice, the Lrp5^A214V mutation prevents brown adipose tissue whitening that occurs in Akita mice. Thus, hyperactivation of Lrp5-dependent signaling fully protects bone mass and strength in prolonged hyperglycemia and improves peripheral glucose metabolism in an insulin independent manner. Wnt signaling activation represents an ideal therapeutic approach for diabetic patients at high risk of fracture. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Bone fragility in patients with diabetes mellitus: A consensus statement from the working group of the Italian Diabetes Society (SID), Italian Society of Endocrinology (SIE), Italian Society of Gerontology and Geriatrics (SIGG), Italian Society of Orthopaedics and Traumatology (SIOT)

Bone fragility is one of the possible complications of diabetes, either type 1 (T1D) or type 2 (T2D). Bone fragility can affect patients of different age and with different disease severity depending on type of diabetes, disease duration and the presence of other complications. Fracture risk assessment should be started at different stages in the natural history of the disease depending on the type of diabetes and other risk factors. The risk of fracture in T1D is higher than in T2D, imposing a much earlier screening and therapeutic intervention that should also take into account a patient's life expectancy, diabetes complications etc. The therapeutic armamentarium for T2D has been enriched with drugs that may influence bone metabolism, and clinicians should be aware of these effects. Considering the complexity of diabetes and osteoporosis and the range of variables that influence treatment choices in a given individual, the Working Group on bone fragility in patients with diabetes mellitus has identified and issued recommendations based on the variables that should guide screening of bone fragility and management of diabetes and bone fragility: (A)ge, (B)MD, (C)omplications, (D)uration of disease, & (F)ractures (ABCD&F). Consideration of these parameters may help clinicians identify the best time for screening, the appropriate glycaemic target and anti-osteoporosis drug for patients with diabetes at risk of or with bone fragility.

Investigation of Mechanical, Material, and Compositional Determinants of Human Trabecular Bone Quality in Type 2 Diabetes

CONTEXT

Increased bone fragility and reduced energy absorption to fracture associated with type 2 diabetes (T2D) cannot be explained by bone mineral density alone. This study, for the first time, reports on alterations in bone tissue's material properties obtained from individuals with diabetes and known fragility fracture status.

OBJECTIVE

To investigate the role of T2D in altering biomechanical, microstructural, and compositional properties of bone in individuals with fragility fracture.

METHODS

Femoral head bone tissue specimens were collected from patients who underwent replacement surgery for fragility hip fracture. Trabecular bone quality parameters were compared in samples of 2 groups, nondiabetic (n = 40) and diabetic (n = 30), with a mean duration of disease 7.5 ± 2.8 years.

RESULTS

No significant difference was observed in aBMD between the groups. Bone volume fraction (BV/TV) was lower in the diabetic group due to fewer and thinner trabeculae. The apparent-level toughness and postyield energy were lower in those with diabetes. Tissue-level (nanoindentation) modulus and hardness were lower in this group. Compositional differences in the diabetic group included lower mineral:matrix, wider mineral crystals, and bone collagen modifications-higher total fluorescent advanced glycation end-products (fAGEs), higher nonenzymatic cross-link ratio (NE-xLR), and altered secondary structure (amide bands). There was a strong inverse correlation between NE-xLR and postyield strain, fAGEs and postyield energy, and fAGEs and toughness.

CONCLUSION

The current study is novel in examining bone tissue in T2D following first hip fragility fracture. Our findings provide evidence of hyperglycemia's detrimental effects on trabecular bone quality at multiple scales leading to lower energy absorption and toughness indicative of increased propensity to bone fragility.

The Impact of Antiosteoporotic Drugs on Glucose Metabolism and Fracture Risk in Diabetes: Good or Bad News?

Osteoporosis and diabetes mellitus represent global health problems due to their high, and increasing with aging, prevalence in the general population. Osteoporosis can be successfully treated with both antiresorptive and anabolic drugs. While these drugs are clearly effective in reducing the risk of fracture in patients with postmenopausal and male osteoporosis, it is still unclear whether they may have the same efficacy in patients with diabetic osteopathy. Furthermore, as bone-derived cytokines (osteokines) are able to influence glucose metabolism, it is conceivable that antiosteoporotic drugs may have an effect on glycemic control through their modulation of bone turnover that affects the osteokines’ release. These aspects are addressed in this narrative review by means of an unrestricted computerized literature search in the PubMed database. Our findings indicate a balance between good and bad news. Active bone therapies and their modulation of bone turnover do not appear to play a clinically significant role in glucose metabolism in humans. Moreover, there are insufficient data to clarify whether there are any differences in the efficacy of antiosteoporotic drugs on fracture incidence between diabetic and nondiabetic patients with osteoporosis. Although more studies are required for stronger recommendations to be issued, bisphosphonates appear to be the first-line drug for treatment of osteoporosis in diabetic patients, while denosumab seems preferable for older patients, particularly for those with impaired renal function, and osteoanabolic agents should be reserved for patients with more severe forms of osteoporosis.

Nutritional Therapy for Athletes with Diabetes

Diabetes is a worldwide disease also affecting the sports field. The two main forms of diabetes, namely type 1 diabetes (T1D) and type 2 diabetes (T2D), differ in both their pathological and pharmacological characteristics and thus require a distinct nutritional treatment. Diet plays an important role in the management of athletes with diabetes and is crucial to achieving their best performance. This review aims to investigate the objectives of nutritional therapy before, during and after training, in order to improve the best composition of macronutrients during meals. In this review, we provide a brief overview of recent studies about nutritional approaches to people with diabetes for performance optimization and for the control of diabetes-related complications. Thereafter, we discuss the differences between macronutrients and dietary intake before, during and after training. It can be concluded that each sport has particular characteristics in terms of endurance and power, hence demanding a specific energy expenditure and consequent nutritional adjustments. Therefore, the management of athletes with diabetes must be personalized and supported by medical professionals, including a diabetologist, physiologist and a nutritionist.